Tripling The Airflow Into a Duramax With Compound Turbos
The quest to build the most powerful Duramax engine on earth is a lofty goal. While Dmitri Millard (2010 Diesel Power Challenge winner) has never actually said that’s his mission—he’s clearly in the running for the title.
| maximum Flow 2001 Chevy Silverado
Some of you may be familiar with Millard’s 1,200hp, ’01 Silverado street truck. It was powered by a max-effort LB7 Duramax featuring compound turbochargers from PPE. We showed you that setup in “The Truth About Twin Turbos” (July ’10), and Millard successfully campaigned the combo on dragstrips and dynos across the country. But for 2012, he swapped that engine into a regular-cab pickup—and this one is a dedicated race rig.
| Dmitri Millard’s Chevy race truck began life with compound turbos (a 106mm Garrett GT5541 and an 80mm GT4508), a PPE Dual Fueler, and a Duramax long-block from his street truck. Millard wanted more power, so PPE recommended upgrading the primary turbo to a GTX4508R.
Millard’s race truck is called Overkill, which you caught a glimpse of in our July ’12 issue. This Silverado started life with his street truck’s compound turbos, but virtually every part of that kit has been massaged from what we showed you two years ago. For this article, PPE added new up-pipes and a second wastegate, and upgraded the primary turbo to a Garrett GTX version.
We followed along while PPE’s Corey Macha transformed Overkill’s engine compartment days before Millard competed at the NHRDA Diesel Texas Nationals where he made a record run. Millard’s Overkill now holds the quickest e.t. record for an Allison-transmission-equipped truck at 9.776 seconds at 148.6 mph. Once Millard gets ahold of a solid track, look for Overkill to go even faster!
| Millard is seen here using an engine hoist to remove the original Garrett GT5541 turbo while it was still connected to its support frame and exhaust inlet manifold.
